title: Relation between the vasodilator-stimulated phosphoprotein phosphorylation assay and light transmittance aggregometry in East Asian patients after high-dose clopidogrel loading.
abstract: OBJECTIVE
  We analyzed the relation between platelet aggregation measured by light transmittance aggregometry (LTA) and platelet reactivity index (PRI) measured by vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) assay.
  
  
  BACKGROUND
  It has been suggested that LTA and VASP-P assay correlate differently according to the level of P2Y12 receptor blockade by thienopyridines.
  
  
  METHODS
  We simultaneously measured platelet function by LTA and VASP-P assay in 466 East Asians undergoing elective percutaneous coronary intervention after a 600-mg clopidogrel loading. High on-clopidogrel platelet reactivity (HPR) was defined by published consensus criteria.
  
  
  RESULTS
  The degree of correlation between LTA and the VASP-P assay was different according to PRI levels. The correlation was lower in patients with poor responsiveness (PRI >60%) (n = 216) (0.035 ≤ r(2) ≤ 0.047), which was greater in responsive patients (PRI ≤60%) (n = 250) (0.315 ≤ r(2) ≤ 0.526). Despite a 600-mg loading, East Asians had a high prevalence of HPR (40.1%-63.5%), and the prevalence of HPR also differed between LTA and VASP-P assay. A PRI cutoff of >58% (area under curve, 0.829; 95% confidence intervals, 0.792-0.862; P < .001) corresponded to the published HPR cutoff by 5-μM adenosine diphosphate-induced maximal platelet aggregation >46%.
  
  
  CONCLUSIONS
  This is the largest study correlating platelet reactivity measured by LTA and VASP-P assay in a percutaneous coronary intervention-treated cohort. The correlation is dependent on the level of responsiveness. Future investigations are needed to better define the optimal cutoffs of HPR measured by LTA and VASP-P assay for personalized antiplatelet therapy.
authors.affiliation: Department of Laboratory Medicine, Medical Research Institute, Busan National University Hospital, Busan, South Korea.
authors.forename: In-Suk
authors.initials: IS
authors.lastname: Kim
authors.forename: Young-Hoon
authors.initials: YH
authors.lastname: Jeong
authors.forename: Udaya S
authors.initials: US
authors.lastname: Tantry
authors.forename: Yongwhi
authors.initials: Y
authors.lastname: Park
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Lee
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Bliden
authors.forename: Jin-Sin
authors.initials: JS
authors.lastname: Koh
authors.forename: Jeong Rang
authors.initials: JR
authors.lastname: Park
authors.forename: Jae-Sik
authors.initials: JS
authors.lastname: Jang
authors.forename: Seok-Jae
authors.initials: SJ
authors.lastname: Hwang
authors.forename: Eun-Ha
authors.initials: EH
authors.lastname: Koh
authors.forename: Choong Hwan
authors.initials: CH
authors.lastname: Kwak
authors.forename: Jin-Yong
authors.initials: JY
authors.lastname: Hwang
authors.forename: Sunjoo
authors.initials: S
authors.lastname: Kim
authors.forename: Paul A
authors.initials: PA
authors.lastname: Gurbel
mesh_terms: D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000097:blood*; D000077144:Clopidogrel; D003324:Coronary Artery Disease / Q000097:blood / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008840:Microfilament Proteins / Q000097:blood*; D008875:Middle Aged; D010750:Phosphoproteins / Q000097:blood*; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage; D010979:Platelet Function Tests; D011446:Prospective Studies; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; D000098662:Vasodilator-Stimulated Phosphoprotein; D000077144:Clopidogrel; D013988:Ticlopidine